Stem Cell and Cloning Glossary of Terms

Dr. David A. Prentice

Dr. David A. Prentice is Senior Fellow for Life Sciences at Family Research Council, a Washington, D.C.-based think tank; and an Affiliated Scholar for the Center for Clinical Bioethics, Georgetown University Medical Center. Until July 2004 he was Professor of Life Sciences at Indiana State University, and Adjunct Professor of Medical and Molecular Genetics for Indiana University School of Medicine. He is a Founding Member of Do No Harm: The Coalition of Americans for Research Ethics, a Fellow of the Wilberforce Forum Council for Biotechnology Policy, a Fellow of the Institute on Biotechnology and the Human Future, and an Advisory Board Member for the Center for Bioethics and Human Dignity. Dr. Prentice received his Ph.D. in Biochemistry from the University of Kansas, and was at Los Alamos National Laboratory and the University of Texas Medical School-Houston. He has taught courses ranging from non-majors biology to advanced courses including developmental biology, embryology, cell and tissue culture, history of biology, science and politics, pathophysiology, medical genetics, and medical biochemistry. His research investigates cell growth control; one focus is adult stem cells. Dr. Prentice is an internationally-recognized expert on stem cell research and cloning, and has testified before the U.S. Congress and numerous state legislatures, the U.S. National Academy of Sciences, the President's Council on Bioethics, European Parliament, British Parliament, Canadian Parliament, Australian Parliament, German Bundestag, French Senate, Swedish Parliament and United Nations.

Adult Stem Cell: A stem cell from organs and tissues after birth (including umbilical cord and placenta) that can renew itself and transform into other specialized cell types.Assisted reproductive technology: Fertility treatments that involve a laboratory handling eggs or embryos, such as in vitro fertilization.Blastocyst: A pre-implantation embryo, approximately 5-7 days after conception (50-150 cells.)Cell Fusion: Merging of two cells into one, creating a hybrid cell. The hybrid usually takes on characteristics from both of the original cells.Cloning: The creation of an animal or person that derives its genes from a single other individual; “asexual reproduction”. Creating a copy that is virtually identical to the original (can be done with molecules, cells, and whole organisms.)Chromosomes: Contain genes, working stretches of DNA that carry the genetic code for specific proteins. Normal human cells contain 46 chromosomes; mature normal human gametes have 23 chromosomes.Differentiation: The process by which early unspecified cells acquire the features of specific cells such as heart, liver, muscle, or brain tissue.DNA: Abbreviation for deoxyribonucleic acid. The genetic material that contains the instructions for making an entire organism.Embryo: The earliest stage of human development, from the single cell zygote up to about 8 weeks.Embryonic germ cell: A cell in the embryo/fetus that normally develops into mature gametes.Embryonic stem cell: A cell from the inner group of cells of a blastocyst, with the potential to become most or all of the body tissues.Fetus: The human being from 8 weeks after conception to birth.Gamete: A mature germ cell, egg (oocyte) or sperm, which unites with another in sexual reproduction.Gene: A unit of heredity that is a segment of DNA located on a specific site on a chromosome.Germ cell: Egg (oocyte) or sperm.In vitro: Done outside of the body.In vivo: Done within the living body.Multipotent: Capable of giving rise to several specialized cells or tissues of an organism.Nucleus: The core of a cell that contains the chromosomes (genetic material.)Parthenogenesis: Creation of an embryo using only an oocyte. The oocyte is stimulated chemically so that it retains 2 sets of chromosomes. (Human oocytes retain 2 sets of chromosomes until fertilized by a sperm; at that point, one set is ejected and the remaining set combines with the sperm chromosomes to form the new genome.)Plasticity: The ability of a stem cell to change into other cell types.Pluripotent: Capable of giving rise to most tissues of the adult body.Regenerative Medicine: Repair or replacement of damaged and diseased tissue through the use of stem cells to regenerate the cells and tissues.“Reproductive Cloning” (Live-Birth Cloning): All cloning is “reproductive” in that it creates—reproduces—a new developing organism intended to be virtually identical to the cloned subject. The term “reproductive cloning” has been used to signify the implantation into a womb of a cloned embryo, in hopes of a live birth.Somatic cell: Cell of the body other than a gamete (other than an egg or sperm.)Somatic cell nuclear transfer: The transfer of a cell nucleus from a body cell into an egg from which the chromosomes have been removed or inactivated; method used for cloning of an organism. Once the transferred genome is within the egg cell and a one-cell embryo is created, the process of cloning is complete and further development of the clone can occur.Stem cells: Non-specialized cells that have the capacity to self-renew and to transform into other mature cell and tissue types.“Therapeutic Cloning” (Research Cloning): Creating a cloned embryo and growth to the blastocyst stage, for the purpose of harvesting embryonic stem cells.Tissue or cell culture: Growth of cells or tissues in a laboratory dish for experimental research.Totipotent: Capable of giving rise to all tissues and organs, including placenta.Zygote: A one-cell embryo.